The goal of this project is to develop a miniaturized, pediatric version of the TORVADTM, a unique ventricular assist system that delivers low-shear, synchronous, pulsatile flow, using controlled piston motion within a toroidal chamber. Low shear is achieved by the relatively low piston speed in conjunction with localized hydrodynamic bearings that maintain bulk piston-torus gap at a fixed distance. The TORVAD synchronizes with the heart to preserve aortic valve flow and maintains autoregulation of cardiac output by the Frank-Starling mechanism. The design of the TORVAD also allows for inherent determination of differential pump pressure, without additional sensors, which can be used to manage patient's medications and flow rates. These advantages have been confirmed in preliminary studies with an adult TORVAD. In vitro tests have demonstrated that the low-shear design preserves high-molecular-weight von Willebrand factor and results in significantly reduced hemolysis as compared to a continuous flow device. In addition, hemodynamic compatibility has been demonstrated using acute and chronic animal models. The TORVAD's hematological results are unmatched by any other ventricular assist device. These preliminary findings demonstrate that the TORVAD has the potential to reduce bleeding, thrombus formation, and strokes that are associated with the use of other ventricular assist devices. The goal of this project is to develop a pediatric version of the TORVAD to be used in patients with body surface area (BSA) between 0.6 and 1.5 m2. The feasibility of a pediatric TORVAD has been demonstrated through the development and testing of the adult version, where computational models for hemodynamics, heat transfer, motor design, fluid dynamics, and magnetostatics were used to design, fabricate, and verify performance with the assembled pump. For this work we will (1) Use the established computational design methodology to miniaturize the device for pediatric patients with a BSA between 0.6 and 1.5 m2; (2) Fabricate five devices and perform design verification; (3) Conduct in vitro experiments to assess hemolysis, high-molecular-weight von Willebrand factor preservation, and platelet activation; and (4) Perform three acute animal experiments to assess implantability, hemodynamic performance, and synchronization.